1. Technical Field
The inventive concept relates to a semiconductor integrated device, and more particularly, to a resistive memory device, a memory apparatus and a data process'ng system having the same.
2. Related Art
Resistive memory devices use a variable resistive material that switches between at least two different resistance states by a rapid resistance change based on an applied voltage. Resistive memory devices have received attention as next-generation memories that can replace dynamic random access memories (DRAMs) or flash memories.
Phase-change memory devices are an example of a resistive memory device. In general, a phase-change memory device includes an access device, a lower electrode formed on the access device, a variable resistive material formed on the lower electrode, and an upper electrode formed on the variable resistive material.
The phase-change memory device stores data by changing a crystalline state of the variable resistive material when current is applied to the lower electrode. The variable resistive material has a low resistance when in a crystalline state and a high resistive when in an amorphous state.
FIG. 1 is view illustrating a structure of a general phase-change memory device.
As shown in FIG. 1, the general phase-change memory device includes an access device 11, a lower electrode 13, a variable resistive material layer 15, and an upper electrode 17 and is fabricated in a confined structure due to increase in a reduction rate. The reference numeral 19 is an insulating layer.
The variable resistive material layer 15 may be formed using germanium-antimony-tellurium (Ge2Sb2Te5; “GST”). Even though GST is widely used as the typical variable resistive material, a transition speed between the crystalline state and the amorphous state is low and thus, overall operation speed of the memory device is lowered. Further, GST has a high melting temperature and thus, high reset current is necessary.
Therefore, there is a need for a memory device using a variable resistive material having a fast transition speed and a low reset current.